Preventing Blood Clots: Risks from Long Flights and More

Tuesday, March 10, 2009

ROCHESTER, Minn. — Long, cramped airline flights aren't the only risk factor for deep vein thrombosis (DVT), the medical term for blood clots in the legs. For those at high risk, hospitalization or surgery is more likely to trigger clot formation than flying.

The March issue of Mayo Clinic Health Letter covers risk factors for deep vein thrombosis, as well as prevention, symptoms and treatment.

For most healthy adults, deep vein thrombosis is extremely rare. Every year, about 350,000 Americans are affected by DVT or a pulmonary embolism, where a clot breaks away and blocks the lung artery — often a fatal condition.

DVT develops in the larger, "deep" veins that are the final conduits funneling blood back to the heart. The condition occurs usually in the largest veins of the legs and pelvis. Many factors increase risk, including certain cancers, advanced age, living in a nursing home, use of hormone replacement therapy, pregnancy, recent childbirth, a family history of DVT, and obesity.

Any of several situations can trigger deep vein thrombosis. Airplane rides lasting six hours or more and long periods of sitting for any reason pose risks. That's why travelers are urged to stretch or walk every hour and stay well hydrated during long flights. Hospitalization for a sudden medical problem also creates risks. Trauma or a fracture in the leg area or pelvis puts patients at especially high risk. Major surgery is in the same category, especially surgery that involves hip and knee replacement or is in the pelvic area.

Many DVTs can develop and grow quite large before symptoms appear. Eventually, in most cases, symptoms are present and can include:

• Swelling in the ankle area of the affected leg. Typically only one leg is affected.
• Leg pain that often starts in the calf and can feel like a cramp.
• Redness or warmth over the affected area and fever.

These symptoms should prompt a visit with a physician. Ultrasound and other imaging technology are used to diagnose DVT. Treatment for deep vein thrombosis seeks to prevent the clot from becoming bigger and to reduce the risk of pulmonary embolism. Most people with DVT are prescribed anticoagulant medications to take for a minimum of three months.

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